Compressors

ABSTRACT

An improved compressor with at least three stages and having at least one cylinder, wherein the improvement comprises that only one connecting rod is used for each cylinder and that the differential piston forms a guide piston for the high-pressure piston, wherein the high-pressure cylinder operates without an inlet valve and its outlet valve covers substantially the entire and face; the invention also comprises a multicylinder arrangement embodying these improvements.



1. A multistage compressor comprising, a. a low-pressure cylinder chamber having one end communicating with a high-pressure cylinder chamber, b. a third chamber communicating with the other end of the lowpressure chamber, said third chamber having a diameter smaller than that of the low-pressure chamber, c. a differential piston having portions of two different diameters, the larger diameter portion carrying piston rings and being slidable within the said low-pressure chamber and the smaller diameter portion carrying piston rings and being slidable within the said third chamber, d. a high-pressure piston connected to the larger diameter portion of the differential piston, said high-pressure piston carrying piston rings at its free end and being slidable within the high-pressure chamber, e. sealing means carried by the high-pressure chamber and cooperating with the high-pressure piston to seal the lowpressure chamber from the high-pressure chamber, f. a first inlet valve and a first outlet valve at that end of the low-pressure chamber which is proximate to the highpressure chamber, g. a second inlet valve and a second outlet valve at the other end of the low-pressure chamber, h. means forming a first air passageway between the said first outlet valve and the said second inlet valve, i. means forming an inlet opening to the high-pressure chamber, which opening is positioned slightly above the lower dead center point of said high-pressure piston, j. means forming a second air passageway between the said second outlet valve and the inlet opening to the high-pressure chambEr, k. a third outlet valve at the end of the high-pressure chamber, and l. drive means for applying reciprocating movement to the differential piston.
 2. The invention as recited in claim 1, including a crankcase communicating with the said third chamber and carrying a supply of oil; and wherein the said drive means comprises a connecting rod connected to the smaller diameter portion of the differential piston and to a crankshaft, said crankshaft dipping into the oil as it is revolved.
 3. The invention as recited in claim 1, wherein the high-pressure piston is rigidly secured to the differential piston.
 4. The invention as recited in claim 1, including means forming an axial hole in the larger diameter portion of the differential piston, which hole terminates in an enlarged diameter bore, an integral flange formed on the high-pressure piston and positioned in said bore, a resilient washer disposed between said flange and the base of the bore, and means retaining the said flange and the washer within the said bore.
 5. The invention as recited in claim 1, wherein the said sealing means comprises an annular groove formed in inner wall of the high-pressure chamber, a resilient O-ring within said groove, and a polytetrafluorethylene washer having a rectangular cross section and disposed between the O-ring and the high-pressure piston.
 6. The invention as recited in claim 1, including a valve seat formed on the end of the high-pressure chamber; and wherein the said outlet valve at the end of the high-pressure chamber comprises a tapered valve body, the small diameter of said body being substantially the same as that of the high-pressure piston.
 7. The invention as recited in claim 1, including a cylinder head comprising a first member constituting a closure plate for the low-pressure chamber and a second member secured to and concentric with the said first member; wherein the said first member carries the said inlet valve and said first outlet valve and includes a tubular portion which constitutes the high-pressure chamber, and wherein the said second member includes means forming a portion of the said first air passageway and means forming a portion of the said second air passageway.
 8. The invention as recited in claim 7, wherein the said means forming an inlet opening to the high-pressure chamber comprises an annular groove formed in the said second member of the cylinder head, wherein the said groove communicates with radial holes passing through the said tubular member; and including a pair of annular seals positioned between the said first and second members and disposed to either side of the said annular groove.
 9. The invention as recited in claim 8, including a crankcase communicating with the said third chamber and carrying a supply of oil; wherein the said drive means comprises a connecting rod connected to the smaller diameter portion of the differential piston and to a crankshaft, said crankshaft dipping into the oil as it is revolved, and wherein said cylinder head is provided with an oil-mist supply passageway communicating at one end with the said first inlet valve and at the other end with the crankcase at a point above the level of the oil.
 10. The invention as recited in claim 1, in combination with a second, similar multistage compressor, a single crankcase communicating with each of the third chambers of the two compressors and carrying a supply of oil, a crankshaft dipping into the oil as it is revolved, and connecting rods connecting the differential pistons of the two compressors to the crankshaft.
 11. The invention as recited in claim 10, wherein the outlet valves at the ends of the high-pressure chambers of the two compressors are connected by a conduit to form a common outlet for the two compressors.
 12. The invention as recited in claim 10, wherein the said means forming the second air passageway also communicates with the corresponding outlet valve of the second compressor, and wherein the inlet opening tO the high-pressure chamber of the second compressor is connected by a conduit to the outlet valve at the end of the high-pressure chamber of the other compressor. 